Simplified piston slidable in a cylinder

ABSTRACT

A simplified piston ( 14 ), slidable in a cylinder ( 16 ), moved by magnetic coupling to an external magnetic element ( 20 ) which moves along the cylinder ( 16 ).

The present invention relates to a simplified piston slidable in acylinder.

In the prior art, there are numerous known types of pistons forcylinders, for example those used in machines of the reciprocating typesuch as reciprocating compressors.

Such a piston, which slides in an essentially guided way in a cylinder,typically comprises a piston body fitted on at least one rod which isgenerally central.

The cylinder is generally closed at its two bases, but has an aperturefor the shaft which emerges from the cylinder in such a way that motioncan be transmitted to the piston body; for example, in the case of areciprocating compressor, the rod is moved by a reciprocating motor.

A mechanical seal must be provided around this aperture to preventleakage of the fluid contained in the cylinder or, conversely, the entryof dirt into the cylinder from the exterior.

The mechanical seal is an element which must be correctly managed andkept in good condition, especially in the case of operations with fluidswhich are environmentally polluting and harmful to persons.

The object of the present invention is therefore to overcome theaforementioned problems and in particular that of providing a simplifiedpiston slidable in a cylinder but which has no operating rod andtherefore no corresponding mechanical seals.

Another object of the present invention is to provide a simplifiedpiston slidable in a cylinder and which is particularly reliable,functional and relatively inexpensive.

These and other objects of the present invention are achieved with asimplified piston slidable in a cylinder as described in claim 1.

Further characteristics of a simplified piston slidable in a cylinderare described in the subsequent claims.

The characteristics and advantages of a simplified piston slidable in acylinder according to the present invention will be made clearer by thefollowing description, provided by way of example and withoutrestrictive intent, with reference to the attached schematic drawing inwhich:

FIG. 1 is a lateral and cross-sectional view of a reciprocatingcompressor which includes a simplified piston slidable in a cylinderaccording to the present invention.

With reference to FIG. 1, this shows a reciprocating compressor,indicated as a whole by 12, which includes a simplified piston 14slidable in a cylinder 16 according to the present invention.

In the illustrated example, according to the present invention, thereciprocating compressor 12 is double-acting, and the piston 14 has nocentral operating rod.

The piston 14 is made from metallic material and is slidable in acylinder 16 which is made from a nonmagnetic material.

An external magnetic element 20, such as a ring, slidable externallyalong the cylinder 16, is also provided. The magnetic element 20 ismoved, for example, by a reciprocating motor of the pneumatic type,which is not shown in the figure.

The operation of the simplified piston 14 slidable in a cylinder 16according to the invention is clear from what has been described abovewith reference to the figure, and is briefly as follows.

The motion is transmitted to the piston 14 by magnetic coupling from theexterior of the cylinder 16 of nonmagnetic material, by means of themagnetic element 20.

The magnetic element 20 is moved along and outside the cylinder 16.

The magnetic field of the magnetic element 20 moves the piston 14, whichis generally made from metallic material or other material sensitive tothe magnetic field.

The absence of any seal in contact with the exterior makes thereciprocating compressor constructed with the piston 14 according to theinvention, without a rod, particularly suitable for applications wheredangerous gases and high pressures are used.

The very high reliability of the piston 14 according to the inventionmakes it suitable for numerous applications with all types of gas orliquid.

The characteristics of the simplified piston slidable in a cylinderaccording to the present invention, and the advantages thereof, will beclearly understood from the above description.

The following concluding remarks and observations will be made in orderto define the aforesaid advantages more precisely and clearly.

In the first place, it should be noted that the simplified pistonslidable in a cylinder according to the invention can be convenientlyused in applications in which a polluting or harmful process fluid isused.

It is also pointed out that the simplified piston slidable in a cylinderaccording to the invention is simple and reliable in use and isinexpensive by comparison with the prior art.

Finally, it is clear that the simplified piston slidable in a cylinderdesigned in this way can be modified and varied in numerous ways, allwithin the scope of the invention; furthermore, all the components canbe replaced by technically equivalent elements. In practice, thematerials used and the forms and dimensions can be chosen at will,subject to technical requirements.

1. Simplified piston slidable in a cylinder, characterized in that it ismoved by magnetic coupling to an external magnetic element which movesalong the said cylinder.
 2. Piston according to claim 1, characterizedin that the said external magnetic element is a ring which is movedoutside the said cylinder.
 3. Piston according to claim 1, characterizedin that the said cylinder is made from a nonmagnetic material.
 4. Pistonaccording to claim 1, characterized in that it is made from a materialsensitive to a magnetic field.
 5. Piston according to claim 4,characterized in that it is made from a metallic material.
 6. Pistonaccording to claim 1, characterized in that it is used in areciprocating machine.
 7. Piston according to claim 6, characterized inthat the said reciprocating machine is a reciprocating compressor. 8.Piston according to claim 1, characterized in that the said externalmagnetic element is moved by a reciprocating motor.
 9. Piston accordingto claim 8, characterized in that the said reciprocating motor is of thepneumatic type.
 10. Piston according to claim 8, characterized in thatit is not provided with a central operating rod.
 11. Piston according toclaim 1, characterized in that the said cylinder has no seal in contactwith the exterior.
 12. Piston according to claim 7, characterized inthat the said reciprocating compressor is double-acting.